1. Field of the Invention
This invention relates generally to ankle orthoses, and particularly to an ankle orthosis intended to brace or support the ankle against inversion, for the prevention and rehabilitation of inversion injuries.
The great majority of ankle injuries occur to the lateral side as a result of inversion, and ankle injuries caused by inversion are a problem for a great many people, particularly athletes. In many cases, such injuries can become chronic, with each successive injury further weakening the ankle and leading to increased susceptibility to further injury. While the series of hindfoot joints, namely the midtarsal, the subtaler, and the talocrural (ankle) joints, function mainly as a hinge in plantar and dorsi flexion, they do allow some eversion and inversion. The lateral malleolus within the ankle joint tends to prevent excessive eversion unless the eversive force is strong enough to cause its fracture. The medial malleolus, however, will not prevent inversion to the same degree due to its shorter length. The lateral ligaments are also much weaker than their medial counterparts. Inversion injuries are therefore very common.
Accordingly, there is a need for a suitable orthosis to aid in preventing inversion injury, and to assist in the rehabilitation of such injuries. The ideal ankle orthosis should be light, durable, and easy to use. It should permit a certain range of motion in order to allow normal function. In the post-traumatic condition, this range, particularly in the coronal plane, must be controlled to stabilize the joint, provide proprioceptive input, and reduce pain with motion. At the same time the orthosis must allow some movement for functional healing to occur. It should be possible to wear the orthosis within a shoe or boot. There should be resistance to decay of functional effectiveness during exercise.
2. Description of the Prior Art
Most ankle supports in the prior art can be delineated by both their structure and the materials used. There are non-rigid devices such as adhesive tape, with its multiple techniques of application, high top shoes, elastic wraps, and lace-up sleeves and boots. These are designed primarily for the prevention of injury. There are also rigid devices which limit ankle motion drastically. They are typically made of orthoplast, polyethylene and polypropylene, which have little flexibility or functional motion.
One of the most commonly used techniques, in athletics in particular, is the use of tape to wrap the ankle. While such taping offers some psychological protection and some physical protection, its effectiveness is limited. Taping is expensive in the long run, its effectiveness degrades gradually during exercise, and movement of the ankle is restricted generally. Other existing braces, such as those described in U.S. Pat. No. 3,506,000 (Baker), U.S. Pat. No. 3,490,450 (Gardner), and U.S. Pat. No. 3,674,023 (Mann), are generally either too cumbersome or too restrictive of movement, or tend to either hinder or excessively allow a complex range of motion of the ankle.
It is an object of the present invention to provide an ankle orthosis which offers advantages over those in the prior art.